Patients with gyrate atrophy of the retina are examined systematically to confirm the diagnosis. Lymphocytes from the patient's blood are isolated, transformed in tissue culture, and assayed for ornithine aminotransferase activity. Skin fibroblasts grown in tissue culture are assayed for ornithine aminotransferase. Other enzymatic activities related to ornithine metabolism such as ornithine decarboxylase activity will be measured. The results will be examined for correlation with the presence of homo- or heteroxygozity for the disease trait. Patients will be given pyridoxine to see if the serum concentration of ornithine can be reduced, and, if so, the patient will be classified as a "responder", treatment with pyridoxine will be continued. Responder patients will be observed for arrest in the progress of their disease.